1. Technical Field
The present invention relates to a driving apparatus for driving switching elements of a power conversion circuit, configured such that a series connection of upper-arm and lower-arm switching elements is electrically connected in parallel with a DC power source.
2. Related Art
A known driving apparatus for driving switching elements of a power conversion circuit, as disclosed in Japanese Patent Application Laid-Open Publication No. 2013-143882, assumes active gate control of insulated-gate bipolar transistors (IGBTs) (as the switching elements) forming a three-phase inverter. The active gate control refers to a technique for changing or altering a setting of discharge rate from a higher one to a lower one within a time period from start to completion of discharging of the gate charge.
To avoid the phenomenon where that the upper-arm switching element and the lower-arm switching element are both ON (so called upper-and-lower-arm short-circuit), there is provided a dead time from transition to an OFF state of one of the upper-arm switching element and the lower-arm switching element and transition to an ON state of the other of the upper-arm switching element and the lower-arm switching element.
In the driving apparatus supporting the active gate control, as described later in more detail, an actual dead time may become greater than a dead time assumed at the time of designing. The dead time assumed at the time of designing is determined by leaving a discharge rate set to a lower rate during the discharge process with no active gate control performed to avoid the upper-and-lower-arm short-circuit.
An actual dead time excessively greater than the dead time assumed at the time of designing may cause a current waveform output from the inverter to be much deformed from a waveform (e.g., a sine wave), which may degrade the torque controllability of a rotary machine connected to the inverter.
In consideration of the foregoing, exemplary embodiments of the present invention are directed to providing a driving apparatus for driving switching elements of a power conversion circuit, capable of preventing a dead time from becoming excessively large.